The present invention relates to blood collection apparatus, and more particularly to a suction-type of apparatus for filling a flexible envelope.
Various means are known for drawing up blood samples, and generally fall into two categories. In a first category is the syringe-type of collection apparatus wherein a vein is punctured and a sample withdrawn through a hollow needle. With such an apparatus, samples of relatively large volumes may be taken. The second category of collection means comprises capillary tubes. As their name implies, such tubes are of very small diameter and depend upon capillary action to cause blood to be drawn into the tubes. Such tubes are commonly used to obtain small blood samples, taken from a skin wound made by a pin prick or the like. As is well known, the skin wound technique is preferred in many situations. For instance, frequently with elderly people veins are prone to collapse and the use of a syringe is undesirable. Also, for taking blood samples from infants a skin wound technique is preferred to the use of a syringe since veins are quite small and hard to locate.
Due to the necessarily small diameter of the capillary tubes, their volume is extremely limited. For many procedures it is desirable that a sample comprise at least 200 microliters of blood. This requires the use of a number of capillary tubes; and further, the discharge of samples from many small tubes involves an undesirable amount of re-handling of the blood samples.
An improved, easily controllable pipetter well adapted for the drawing of blood samples is disclosed in co-pending application Ser. No. 876,340, filed Feb. 9, 1978 and entitled "Hand-Held Pipetter". With such a device a flexible reservoir is coupled to a rigid, elongate tube and a roller progressively collapses and then re-distends the reservoir to cause fluid to be drawn into the tube. The fluid is subsequently discharged from the tube into another vessel for treatment, analysis or the like. In order that air be expelled and subsequently drawn into the reservoir both ends thereof are open, and secured in the apparatus housing by means of adapters or the like.
In most cases it has been necessary to discharge the sample from capillary tubes, fillable reservoirs, and the like into another vessel for treatment and/or analysis. In some cases attempts have been made to treat a sample while in a capillary tube; with one approach a tiny ferromagnetic element is disposed within the capillary tube and agitated by placing a magnet adjacent the tube and moving it back and forth. In general such efforts have not been completely successful, and moreover the cost of such devices is relatively high. On the other hand, when the sample must be discharged into another container for treatment valuable time is lost and damage to sample material can occur.
Accordingly, it will be seen that it would be highly desirable to provide a blood sample collection means which serves to fill a detachable reservoir whose volume is considerably greater than that of a capillary tube, and which is adapted for initiating treatment of a blood sample.
Another object of the invention is to provide a blood sample collection device for filling a flexible sample-transporting envelope.
Yet another object is to provide means for drawing a blood sample into a flexible envelope bearing a sample treating agent.
Still another object of the present invention is to provide a blood sample collection apparatus having substantially greater volume than a capillary tube and adapted for drawing blood from a skin wound.